1. Field of the Invention
This invention relates generally to a system and method for providing steering angle control for lane centering and lane changes in an autonomously driven vehicle and, more particularly, to a system and method for providing steering angle control for lane centering and lane changing in an autonomously driven vehicle where a steering angle command is calculated as a simplified function of vehicle lateral position, vehicle lateral speed, vehicle yaw rate and vehicle yaw angle.
2. Discussion of the Related Art
The operation of modern vehicles is becoming more autonomous, i.e., the vehicles are able to provide driving control with less driver intervention. Cruise control systems have been on vehicles for a number of years where the vehicle operator can set a particular speed of the vehicle, and the vehicle will maintain that speed without the driver operating the throttle. Adaptive cruise control systems have been recently developed in the art where not only does the system maintain the set speed, but also will automatically slow the vehicle down in the event that a slower moving preceding vehicle is detected using various sensors, such as radar and cameras. Certain modern vehicles also provide autonomous parking where the vehicle will automatically provide the steering control for parking the vehicle. Some vehicle systems intervene if the driver makes harsh steering changes that may affect vehicle stability. Some vehicle systems attempt to maintain the vehicle near the center of a lane on the road. Further, fully autonomous vehicles have been demonstrated that can drive in simulated urban traffic up to 30 mph, observing all of the rules of the road.
As vehicle systems improve, they will become more autonomous with the goal being a completely autonomously driven vehicle. For example, future vehicles probably will employ autonomous systems for lane changing, passing, turns away from traffic, turns into traffic, etc. As these systems become more prevalent in vehicle technology, it will also be necessary to determine what the driver's role will be in combination with these systems for controlling vehicle speed and steering, and overriding the autonomous system.
U.S. patent application Ser. No. 12/143,439, titled “Path Generation Algorithm for Automated Lane Centering and Lane Changing Control System”, assigned to the assignee of this application and herein incorporated by reference, discloses a system and method for providing path generation for lane centering and lane changing purposes in an autonomous or semi-autonomous vehicle. However, in order to be fully functional, the system needs to generate a steering angle in response to the path generation so that the vehicle follows the desired path. Systems known in the art that provide steering angle commands in autonomous vehicle systems typically are complex.